Known as one of optical connector ferrules is an MT (Mechanically Transferable) connector ferrule. This MT connector ferrule has been standardized as IEC60874-16 (1994) and JIS C5981, and comprises a pair of guide holes into which guide pins are inserted and a plurality of fiber holes, disposed between these guide holes, for receiving respective optical fibers.
FIG. 29 shows an example of molding die for molding such an MT connector ferrule. The molding die 60 is constituted by an upper die 69a, a lower die 69b, and an intermediate die 65 inserted therebetween. In the intermediate die 65, a pair of planar holding members 65a, 65b sandwich and hold therebetween two guide hole forming pins 61 for forming optical connector ferrule guide holes. Held between these guide hole forming pins 61 are a pair of holding members 70a, 70b which are thinner and narrower than the holding members 65a, 65b. A plurality of optical fiber hole forming pins 63 projecting from distal ends of the holding members 70a, 70b so as to form optical fiber holes of an optical connector ferrule are arranged. The inner faces of the upper die 69a and lower die 69b are processed so as to form a space corresponding to the outer shape of the optical connector ferrule when all the dies are assembled together, and are further provided with grooves 72, 62 for positioning the respective guide hole forming pins 61, and grooves 64 for positioning the respective optical fiber hole forming pins 63. The lower die 69b is provided with a protrusion 71 for forming a window frame for the ferrule.
When molding an optical connector ferrule by using such a molding die 60, the intermediate die 65 is initially disposed between the upper die 69a and lower die 69b. Specifically, the guide pin forming pins 61 of the intermediate die 65 are placed in the grooves 72 of the upper die 69a and the grooves 62 of the lower die 69b, and the optical fiber hole forming pins 63 are arranged in the grooves 64 of the lower die 69b. Here, as shown in FIG. 31, the holding member 70b of the intermediate die 65 is held on the protrusion 71 of the lower die 69b. Then, the space between the upper die 69a and the lower die 69b is filled with a molten resin, which is subsequently set and taken out of the die, whereby the optical connector ferrule can be formed.
Thus formed MT connector ferrule is used for connecting optical fibers on an optical transmission line to each other or an optical fiber to an optical member. Here, not only a method in which MT connector ferrules are connected to each other as they are, a method in which the ferrules are provided with housings so as to be formed into connectors for connection has widely been carried out. Widely known as examples of such optical connectors are a connector (generally known as MPX connector) disclosed in Japanese Translated PCT International Patent Application No. 2000-515986A and a multi-fiber connector (generally known as MPO connector) specified in TIA/EIA-604-5-A. When these multi-fiber connectors are used, devices and wiring systems can be made much smaller and denser than those with single-fiber optical connectors. Therefore, backplane wiring, optical interconnected wiring, and the like using these optical connectors as an interface have widely been in use.